main index

P00: frame around

P01: olicognography

P03: infrastructures

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Registers of application docs

build.struct.haz.

build.soil

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Similar user docs

model.build.

build.project

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const.design

Buildings Settlements Causes Limits Care

Causes of settlement

Value of angular distorsion

cause

comment

δ : settlement

Θ: radius of settlement

H: heigh of building

Length basis of building

compression of foundation soils under static loads

soft normally consolidated clays and peaty soils are most compressible. loose

Type of building

L / H

allowable

Compression of soft clays due to lowering ground water table

Increased effective stress causes settlement with no increase in surface load

steel frame with flexible siding

-

0.008

steel or reinforced concrete frame with intensive finish such as dry wall, glass or moveable panels

-

0.002 to 0.003

Compression of cohesion less soils due to vibrations

Loose sands and gravels are most susceptible. Settlement can be caused by machine vibrations, earthquakes and blasts

steel or reinforced concrete frame with brick, block, plaster or stucco finish

≥ 5

≤ 3

0.002

0.001

load bearing brick, tile or concrete blocks walls

≥ 5

≤ 3

0.0008

0.0004

Compression of foundations soil due to wetting

Loose silty sands and gravels are most susceptible. Settlements can be caused by rise in groundwater table or by infiltration

circular steel tanks on flexible base with fixed top

-

0.008

circular steel tanks on flexible base with floating top

-

0.002 to 0.003

Shrinkage of cohesive soils caused by drying

highly plastic calys are most susceptible, increase in temperature under buildings containing ovens or furnaces may accelerate drying. Wetting or highly plastic clays can cause swelling and heave of foundations

tail slender structures, such as stacks, silos, water tanks with rigid mat foundations

-

0.002

Mind

Foundation Possibilities for Different Subsoil Conditions

Loss of foundation support due to erosion

Waterfront foundations must extend below maximum erosion depth

regular / irregular settlem. & radius of settled area


Subsoil conditions

Foundation Possibilities

Loss of foundation support due to excavation of adjacent ground

Mos pronounced in soft saturated clays


Light flexible structure

Heavy rigid structure

Loss of support due to lateral sifting of adjacent ground

Lateral shifting may result from landslides, slow downhill creep or movement of retaining structures


Deep compact or stiff deposit

Footing foundations

1. Footing foundations

2. Shallow mat

Loss of support due to partial or complete liquefaction

Loose saturated sands are most susceptible


Deep compressible strata

1 Footing foundations on compacted granular zone

2. Shallow mat

3. Friction Piles

1. Deep mat with possible rigid construction in basement

2. Long piles or caissons to by-pass

3. Friction piles

Loss of support due to formation of skinhole

Soils overlying cavernous limestone and broken conduits are susceptible


Soft or loose strata overtlying firm strata

1. Bearing piles or piers

2. Footing foundations on compacted granular zone

3. Shallow mat

1. Bearing piles or piers

2. Deep mat

Loss of support due to thawing of permafrost foundation heat

permafrost should be insulated from heat source


Compact and stiff layer overlying soft deposit

1. Footing foundations

2. Shallow mat

1. Deep mat (floating type)

2. Long piles or caisons to by-pass soft deposit

Down drag on piles driven through soft clay

Loading on piles is increased by negative skin friction of soil around upper part of pile settles


Alternating soft and stiff layers

1. Footing foundations

2. Shallow mat

1. Deep mat

2. Piles or caissons to underlying firm stratum

Places of use docs

bamboosociety

build.soil.qual.

carparkingformula

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